An online chlorine analyzer detects the presence of chlorine in water, e.g., water intended for use in dialysis, other medical applications, or for other uses in which chlorine detection is important. For color based detection, an online chlorine analyzer pumps two reagents from bottles through tubes into a chlorine measurement cell, i.e., a colorimeter. The reagents are mixed with the water sample to be analyzed and time is allowed for a color change of a reagent (e.g., N,N Diethyl-1,4 Phenylenediamine Sulfate, “DPD”) in proportion to the amount of chlorine present in the water sample.
The DPD reagents, i.e., a buffer and an indicator, are conventionally delivered in an approximate 1:1 ratio before mixing with the sample water and allowing color development to proceed. Color density is a measure of the chlorine concentration and precise optics are employed to measure the color density change using a calibrated light source and a sensitive photodiode integral to the measurement cell.
To make a trustworthy chlorine determination it is imperative to know that reagent delivery has taken place and that the reagents have been delivered simultaneously in the proper ratio. Proper mixing and delivery of a proper volume of sample water is also important but outside the requirements for reagent delivery detection.